JP6699701B2 - Yttrium-based fluoride thermal spray coating, thermal spray material for forming the thermal spray coating, method of forming the thermal spray coating, and corrosion resistant coating including the thermal spray coating - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention provides a low-dusting corrosion-resistant coating provided on parts or the like used in an atmosphere of halogen-based corrosive gas or corrosive plasma in manufacturing processes such as semiconductor manufacturing, liquid crystal manufacturing, organic EL manufacturing, and inorganic EL manufacturing. The present invention relates to a yttrium-based fluoride sprayed coating, a sprayed material for forming the sprayed coating, a method for forming the sprayed coating, and a multi-layered corrosion-resistant coating including the yttrium-based fluoride sprayed coating.

  Conventionally, in a semiconductor manufacturing process, an insulating film etching apparatus, a gate etching apparatus, a CVD apparatus, etc. are used, but in this case, the corrosion resistance of the chamber member due to plasma generation becomes a problem with the high integration technology by the miniaturization process. Sometimes. Further, in order to prevent contamination of impurities, high-purity materials are used for members constituting these devices.

Fluorine-based or chlorine-based halogen-based gas is used as the processing gas in the semiconductor manufacturing process, and SF ₆ , CF ₄ , CHF ₃ , ClF ₃ , HF, NF _3, etc. are used as the fluorine-based gas, and chlorine-based gas is also used. Examples of the gas include Cl ₂ , BCl ₃ , HCl, CCl ₄ , and SiCl ₄ . High-frequency waves such as microwaves are generated in the atmosphere in which these gases are introduced, and these gases are converted into plasma for processing. At that time, the members constituting the chamber exposed to this plasma are required to have high corrosion resistance. To be done.

  A corrosion-resistant film is formed on the surface of the parts and members of the apparatus used for such treatment. For example, yttrium oxide (Japanese Patent No. 4006596) is formed on the surface of a base material made of metal aluminum or aluminum oxide ceramics. Gazette) and yttrium fluoride (Japanese Patent No. 3523222 gazette, Japanese Patent Laid-Open No. 2011-514933 gazette), the parts and members formed by thermal spraying are known to have excellent corrosion resistance and have been adopted. Further, as a material for protecting the inner wall of the chamber member exposed to plasma, quartz, ceramics such as alumina, an alumite treatment coating, or a thermal spray coating obtained by subjecting the surface of these base materials to the above thermal spraying is mentioned. Further, Japanese Patent Application Laid-Open No. 2002-241971 proposes a plasma resistant member in which a surface region exposed to plasma under a corrosion resistant gas is formed of a metal layer of Group 3A of the periodic table. The film thickness is generally about 50 to 200 μm.

  However, the above-mentioned ceramic member has a high processing cost, and when it is exposed to plasma for a long time in a corrosive gas atmosphere, the reaction gas causes corrosion from the surface to dissociate the crystal grains forming the surface, so-called. Particles are generated. It is known that the separated particles adhere to the semiconductor wafer, the lower electrode, etc. and adversely affect the manufacturing yield in the etching process, and it is necessary to remove the reaction products that cause the particle contamination. Further, even when the surface of the member is made of a material having corrosion resistance to plasma, it is necessary to prevent metal contamination from the base material. Further, in the case of an alumite treatment coating or a thermal spray coating, if the substrate to be coated is a metal, contamination from the metal may adversely affect the quality yield of the etching process.

  On the other hand, it is necessary to remove the reaction product adhered and deposited on the inner wall of the chamber by cleaning due to the influence of plasma, but in the atmospheric water or water-based cleaning step, the reaction product reacts with water to generate an acid, The acid permeates to the interface between the thermal spray coating and the metal substrate and damages the interface of the substrate, leading to a decrease in the adhesive strength at these interfaces, causing film peeling and the risk of impairing the original plasma resistance. is there.

  Further, in the manufacture of semiconductor devices, miniaturization and increase in diameter have been progressing, and particularly the plasma resistance performance of the chamber member has a great influence in the dry etching process, and metal contamination, reaction products and The above particles due to the shedding of particles from the film pose a problem.

  Furthermore, in recent years, the integration of semiconductors has progressed, and the wiring has become 20 nm or less. In the case of the above yttrium-based film, the surface of the yttrium-based film of the component during etching in the manufacturing process of this highly integrated semiconductor device The yttrium-based particles are peeled off and fall on the Si wafer, which becomes an obstacle to the etching process, which causes the yield of semiconductor devices to be deteriorated. Further, the amount of yttrium-based particles peeled off from the surface of the yttrium-based coating is large at the beginning of the etching time and tends to decrease as the etching time becomes longer. In addition to the above, the following patent documents 5 to 9 can be cited as prior art documents.

Japanese Patent No. 4006596 Japanese Patent No. 3523222 Special table 2011-514933 gazette JP, 2002-241971, A Japanese Patent No. 3672833 Japanese Patent No. 490597 Japanese Patent No. 3894313 Japanese Patent No. 5396672 Japanese Patent No. 4985928

  The present invention has been made in view of the above circumstances, and suppresses gas permeation of a halogen-based corrosive gas used in a semiconductor manufacturing apparatus from the surface of the member, and has sufficient corrosion resistance to plasma (plasma resistance). ), the substrate damage due to acid permeation can be prevented as much as possible even if the acid cleaning for removing the reaction product adhered and deposited on the surface of the member during plasma etching is repeated as much as possible, and metal contamination, It is an object of the present invention to provide a corrosion-resistant coating film in which the generation of particles due to the reaction products and the shedding of particles from the coating film is small.

As a result of earnest studies to achieve the above object, the present inventors have a yttrium-based fluoride crystal structure containing YF ₃ , Y ₅ O ₄ F ₇ , YOF, etc., and have an oxygen concentration of 1 to 6 mass. %, hardness of 350 HV or more, yttrium-based fluoride sprayed coating, especially crack amount and porosity 5% or less of the coating surface area, further carbon content of 0.01% by mass or less, sufficient corrosion resistance to plasma It was found that the substrate damage due to the acid permeation can be effectively prevented during the acid cleaning, and the generation of the particles can be reduced as much as possible.

As a result of further studies, the present inventors have found that as a thermal spray material, 9 to 27 mass% of Y ₅ O ₄ F ₇ and the balance of YF ₃ are granulated powder or yttrium fluoride granulated powder 95. To easily form the above high-performance yttrium-based fluoride spray coating having a crack amount of 5% or less by using a mixed powder in which ˜85% by mass and a granulated powder of yttrium oxide of 5 to 15% by mass are used. And a lower layer of a rare earth oxide sprayed coating having a porosity of 5% or less, which is made of an oxide of a rare earth such as Y, Sc, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and the above yttrium fluoride. By combining with a thermal spray coating, it has been found that a higher acid permeation suppression effect can be obtained, the damage of the coating can be more effectively prevented, and a more reliable corrosion resistance performance can be obtained. is there.

Therefore, the present invention provides the following yttrium fluoride thermal spray coating, a thermal spray material for forming the thermal spray coating, a method for forming the thermal spray coating, and a corrosion resistant coating including the thermal spray coating.
[1] A yttrium-based fluoride thermal spray coating having a thickness of 10 to 500 μm formed on the surface of a base material, which has a yttrium-based fluoride crystal structure containing YF ₃ and Y ₅ O ₄ F ₇ and/or YOF. and an oxygen concentration 2-4 wt%, hardness 350~470HV der is, 5% of the cracks weight film surface area or less, and yttrium-based fluorides porosity characterized by 5% der Rukoto coating surface area Thermal spray coating.
[ 2 ] The yttrium fluoride thermal spray coating of [1 ] having a yttrium fluoride crystal structure composed of YF ₃ and Y ₅ O ₄ F ₇ and/or YOF.
[ 3 ] The yttrium fluoride thermal spray coating according to [1] or [2] , which has a carbon content of 0.01 mass% or less.
[ 4 ] A thermal spray material for forming the yttrium fluoride thermal spray coating according to any one of [1] to [ 3 ], wherein 9 to 27 mass% of Y ₅ O ₄ F ₇ and the balance of YF ₃ are granulated. A yttrium-based fluoride thermal spray material characterized by comprising powder.
[ 5 ] A thermal spray material for forming the yttrium-based fluoride thermal spray coating of any one of [1] to [ 3 ], wherein the yttrium fluoride granulated powder 95 to 85 mass% and the yttrium oxide granulated powder 5 A yttrium-based fluoride thermal spray material, characterized in that it is a mixed powder in which 0.1 to 15 mass% is mixed.
[ 6 ] A method for forming the yttrium-based fluoride sprayed coating of any one of [1] to [ 3 ], which is formed by spraying using the yttrium-based fluoride sprayed material according to [ 4 ] or [ 5 ]. A method for forming a yttrium-based fluoride sprayed coating, comprising:
[ 7 ] The method for forming an yttrium-based fluoride sprayed coating according to [ 6 ], wherein the spraying is plasma spraying.
[ 8 ] A lower layer made of a rare earth oxide sprayed coating having a thickness of 10 to 500 μm and a porosity of 5% or less, and an outermost surface layer made of the yttrium fluoride sprayed coating of any one of [1] to [ 3 ]. Corrosion resistant film having a multi-layer structure.
[ 9 ] The rare earth metal element of the lower layer rare earth oxide sprayed coating is one or more selected from Y, Sc, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu [ 8 ]. Corrosion resistant film.

  According to the yttrium-based fluoride sprayed coating of the present invention, while exhibiting excellent corrosion resistance when treated in a halogen-based gas atmosphere or a halogen-based gas plasma atmosphere, substrate damage due to acid penetration even during acid cleaning Can be effectively prevented, and furthermore, the generation of particles due to the reaction products and the shedding of particles from the film can be reduced as much as possible. According to the thermal spray material of the present invention, such an yttrium fluoride thermal spray coating of the present invention can be easily obtained. Furthermore, according to the corrosion resistant coating of the present invention in which the yttrium fluoride thermal sprayed coating of the present invention is combined with the lower layer composed of the rare earth oxide thermal sprayed coating having a porosity of 5% or less, the effect of suppressing acid permeation can be further enhanced. In addition, it is possible to more effectively prevent damage to the coating and obtain more reliable corrosion resistance.

5 is an electron micrograph showing the surface of a yttrium-based fluoride sprayed coating formed in Comparative Example 1. It is the elements on larger scale of the electron micrograph of FIG. 1 which emphasized the crack. 3 is an electron micrograph showing the surface of the yttrium-based fluoride sprayed coating formed in Example 2. FIG. 4 is a partially enlarged view of the electron micrograph of FIG. 3 highlighting cracks.

The thermal spray coating of the present invention is a yttrium fluoride thermal spray coating having good corrosion resistance to a halogen-based gas atmosphere or a halogen-based gas plasma atmosphere, and includes, for example, YF ₃ , Y ₅ O ₄ F ₇ , YOF and the like. Those having a yttrium-based fluoride crystal structure, and preferably those having a yttrium-based fluoride crystal structure composed of YF ₃ and at least one selected from Y ₅ O ₄ F ₇ , YOF, and Y ₂ O _3. Is.

  As described above, the yttrium fluoride thermal spray coating of the present invention is a film having an oxygen concentration of 1 to 6 mass% and a hardness of 350 HV or higher. Thus, a yttrium fluoride thermal spray coating having a low oxygen concentration and high hardness is The film quality has a small number of cracks and open pores, which makes it possible to suppress particle contamination and invasion of halogen-based corrosive gas. In addition, more preferable oxygen concentration is 2 to 4.8 mass %, and more preferable hardness is 350 to 470 HV. The amount of cracks in the coating is preferably 5% or less of the surface area of the coating, and more preferably 4% or less. The porosity is also preferably 5% or less of the surface area of the coating, and more preferably 3% or less. The crack amount and the porosity can be quantified by image analysis of the surface of the sprayed coating, and the ratio to the image area can be measured. When the coating is used in a cut state, the area of its cross-section is also included in the above-mentioned "coating surface area". The details of the crack amount and the porosity and the specific measuring methods thereof will be described later.

  Further, although not particularly limited, it is preferable that the amount of carbon in the film is 0.01% by mass or less, whereby the distortion of the crystal system caused by the influence of carbon and the film quality caused by the influence of plasma gas or heat. Can be suppressed, and the film quality can be stabilized. A more preferable amount of carbon is 0.005% by mass or less.

The yttrium-based fluoride forming the sprayed coating of the present invention does not react with the halogen-based plasma gas and can suppress the generation of particles due to the reaction gas, thereby making it possible to reduce process fluctuations during semiconductor device manufacturing. Can be prevented. The yttrium-based fluoride that forms the sprayed coating of the present invention is not particularly limited, but as described above, at least one selected from YF ₃ and Y ₅ O ₄ F ₇ , YOF, and Y ₂ O _3. It is preferable to have a yttrium-based fluoride crystal structure composed of one or more species.

That is, some rare earth fluorides have a phase transition point due to the rare earth element, and Y, Sm, Eu, Gd, Er, Tm, Yb, and Lu undergo phase change during cooling from the sintering temperature and cracks occur. Therefore, it is difficult to manufacture a sintered body. This is due to the crystal structure. For example, the yttrium fluoride sprayed coating has two types of crystal structures, a high temperature type and a low temperature type, and the transition temperature is 1355K. Phase density by transition surface cracks occur due to a change to the volume decreased from 3.91 g / cm ³ of high temperature (hexagonal) to 5.05 g / cm ³ of low-temperature (orthorhombic). On the other hand, when a small amount of Y ₂ O ₃ , for example, is added to the yttrium-based fluoride, the crystal is partially stabilized and the crack morphology is changed to reduce the surface crack. Further, in the present invention, as described above, a film having a yttrium-based fluoride crystal structure composed of YF ₃ and at least one selected from Y ₅ O ₄ F ₇ , YOF, and Y ₂ O ₃ can be formed. Preferably, this can effectively suppress the occurrence of cracks.

  The thickness of the thermal spray coating of the present invention is 10 to 500 μm, and preferably 30 to 300 μm, as described above. If the thickness of the coating is less than 10 μm, sufficient corrosion resistance to a halogen-based gas atmosphere or a halogen-based gas plasma atmosphere may not be obtained, and it may be difficult to effectively suppress particle contamination. There is also. On the other hand, even if the thickness exceeds 500 μm, the effect corresponding to the increase in thickness is not improved, and inconvenience such as film peeling due to thermal stress may occur.

  The yttrium fluoride thermal spray coating of the present invention can be obtained by performing thermal spraying using the following thermal spray materials.

That is, a mixed raw material powder obtained by mixing 95 to 85 mass% of YF ₃ raw material powder and 5 to 15 mass% of Y ₂ O ₃ raw material powder is granulated by spray drying or the like, and the obtained granulated powder is vacuumed or inert. It is calcined in a gas atmosphere at a temperature of 600 to 1000° C., preferably 700 to 900° C. for 1 to 12 hours, preferably 2 to 5 hours to obtain a single granulated powder. The above is preferably be a single particle of each raw material powder of particle size 0.01 to 3 [mu] m (D _50), the particle size of the fired granulated powder is preferably set to 10 to 60 [mu] m (D ₅₀₎ .. It can be confirmed by XRD analysis that the fired powder (granulated powder) thus obtained has a crystal structure in which Y ₅ O ₄ F ₇ and YF ₃ are mixed, and the content of Y ₅ O ₄ F ₇ is The balance becomes YF ₃ at 9 to 27 mass %. This fired powder (single granulated powder) can be used as a thermal spray material for forming the thermal spray coating of the present invention. Further, an unfired mixed powder obtained by mixing 95 to 85 mass% of the YF ₃ raw material powder (granulated powder) and 5 to 15 mass% of the Y ₂ O ₃ raw material powder (granulated powder) is used as the thermal spray material. You can also

At least one selected from YF ₃ , Y ₅ O ₄ F ₇ , YOF, and Y ₂ O ₃ by performing thermal spraying using the above-mentioned baked powder (single granulated powder) or the above-mentioned mixed powder as a thermal spray material. A thermal sprayed coating having a yttrium-based fluoride crystal structure consisting of and is obtained. The coating has few surface cracks and is a dense coating with a hardness of approximately 350 to 470 HV. Further, the oxygen content in this thermal spray coating is 2 to 4 mass %. Further, by using these thermal spray materials, the porosity described later can be reduced, and the porosity can be 5% or less.

  In the thermal spray coating of the present invention, the crack amount is preferably 5% or less of the coating surface area as described above, but a method of polishing the surface of the obtained thermal spray coating is also effective as a method for reducing the crack amount. Is. That is, a method is also possible in which the surface of the yttrium-based fluoride thermal spray coating formed by thermal spraying is scraped off by a thickness of 10 to 50 μm to remove cracks. However, even if the cracks in the outermost surface layer are removed by polishing, the hardness is low, and if the porosity is large, a dense film quality is not obtained, and even after the cracks are removed by polishing, a high hardness of 350 HV or higher is maintained and the porosity is high. It is necessary that the film quality is small. On the other hand, the advantage of reducing cracks by surface grinding, polishing, etc. is that the surface roughness can be reduced by polishing to reduce the specific surface area of the coating surface and the initial particles can be reduced.

  The spraying conditions for forming the yttrium-based fluoride sprayed coating of the present invention may be any atmosphere such as plasma spraying, SPS spraying, explosive spraying, reduced pressure spraying, etc., and the distance between the nozzle and the base material and the spraying speed ( For example, the above powdery thermal spray material may be charged into a thermal spraying device while controlling the gas species and the gas amount) to form a film having a desired thickness. In that case, especially in the case of plasma spraying, it is advisable to use helium gas as the secondary gas. The reason is that by using helium gas, the speed of the melting frame is increased and a denser film can be obtained.

  The base material on which the yttrium fluoride thermal sprayed coating of the present invention is formed is not particularly limited, but it is usually a metal used in semiconductor manufacturing equipment, ceramics, etc. A base material that has been subjected to alumite treatment having a property may be used.

  As described above, the thermal spray coating of the present invention preferably has a small amount of cracks and a low porosity of 5% or less of the surface area of the coating, and in the present invention, such a low amount of cracks and a low porosity can be achieved. It is possible. The cracks and porosity will be described in more detail below.

  As described in the "Spraying Technology Handbook" (Author: Japan Thermal Spraying Association, Publishing: Technology Development Center, Publication: May 1998), the cross section of the sprayed coating has joints, unbonded portions, and vertical cracks. Exists. Vertical cracks are defined as open pores. If there are closed pores (close pores) existing in the joint and non-joint spaces, gas and acid water will not penetrate, but vertical cracks (open pores) and horizontal cracks (open pores) in the unbonded space will be sprayed. If it is connected to the interface between the film and the substrate, gas and acid water will penetrate to the interface of the substrate. The presence of the open pores (vertical cracks) allows the reaction gas to penetrate to the interface between the thermal spray coating and the substrate. The reaction product generated on the surface of the coating reacts with water to generate an acid, which dissolves in water and permeates into the thermal spray coating, reacts with the base metal at the base material interface, and acts by the reaction gas. The thermal spray coating floats and the coating peels off. It is presumed that this action also occurs in water and acid used in repeated washing. These mechanisms will be described below.

Mixed gas plasma of CCl ₄ , CF ₄ , CHF ₃ , NF ₄ etc. in the polysilicon gate electrode etching of the dry etching process in the semiconductor manufacturing process, mixed gas plasma of CCl ₄ , BCl ₃ , SiCl ₄ etc. in the Al wiring etching, W In the wiring etching, mixed gas plasma of CF ₄ , CCl ₄ , O _2, etc. is used. Further, a SiH ₂ Cl ₂ —H ₂ mixed gas is used for forming a Si film in a CVD process, a SiH ₂ Cl ₂ —NH ₃ —H ₂ mixed gas is used for forming a Si ₃ N ₄ , and a TiCl ₄ —NH ₃ mixed gas is used for forming a TiN film. It is used.

In this case, for example, in the chlorine-based gas plasma in the Al wiring etching, aluminum and chlorine react and aluminum chloride (AlCl ₃ ) adheres to the surface of the sprayed coating as a deposit. The deposits penetrate into the thermal spray coating together with water and accumulate at the interface between the thermal spray coating and the aluminum base material. Then, agglomeration of aluminum chloride occurs at the interface during washing and drying, and aluminum chloride reacts with water to be converted into aluminum hydroxide to generate hydrochloric acid. This hydrochloric acid reacts with the underlying aluminum metal to generate hydrogen gas, floating the sprayed coating at the interface, causing partial destruction of the sprayed coating, and peeling the coating, a so-called film floating phenomenon occurs. At the location where the film floating occurs, the adhesion is extremely reduced. All of these causes are that cracks on the surface of the thermal spray coating and open pores inside the coating (vertical cracks) are continuously connected to the base material interface. The reaction of the film surface reaction product (deposit) AlCl _{3 at} the base material interface is as follows. AlCl ₃ +3H ₂ O→Al(OH) ₃ +3HCl,
Al+3HCl→AlCl ₃ +(3/2)H ₂ ↑

  When the film floating phenomenon occurs, the base material is damaged, the life of the base material is shortened, and various adverse effects are exerted on the manufacturing process. In the present invention, the cracks on the surface of the coating and the open pores in the coating (vertical cracks) can be minimized. That is, as described above, in the present invention, the crack amount and the porosity can be set to 5% or less, and gas, acid water, and reaction products can be effectively prevented from permeating from the surface of the thermal spray coating, and the thermal spraying can be performed. It is possible to prevent the film from peeling off by suppressing the reaction between the film and the metal at the interface between the base and the acid. Here, the "crack" of the amount of cracks in the present invention is a crack existing on the outermost surface of the coating immediately after thermal spraying (cracks), and the "porosity" of the porosity means that the coating cross section is a mirror-polished surface. It refers to existing pores and includes both the open pores and the closed pores. The crack amount and porosity can be measured as follows. Note that it is substantially difficult to measure only open pores, and in the present invention, the porosity including both open pores and closed pores is measured. It is possible to prevent the above-mentioned inconvenience due to pores as much as possible.

That is, several points to several tens points (usually about 5 to 10 points) are uniformly selected from the entire outermost surface of the coating immediately after thermal spraying (in the case of crack amount) or the surface of the coating surface mirror-polished (in the case of porosity). The electron micrographs each having an area of about 0.001 to 0.1 mm ² were obtained, and each electron micrograph was image-processed to combine the ratio (%) of the crack area or the open and closed pores. The ratio (%) occupied by the area is calculated, and the average value is taken as the crack amount or porosity.

As a method of forming a yttrium-based fluoride sprayed coating having a small porosity, in addition to a method of using the above-mentioned baked powder (single granulated powder) or the above mixed powder as a spraying material, explosion spraying or suspension plasma as a spraying method. It is also effective to use thermal spraying (SPS). That is, the flame velocity in the case of plasma spraying is about 300 m/sec when hydrogen is used as the secondary gas and about 500 to 600 m/sec when helium gas is used, whereas it is 1000 to 2500 m/sec in the case of explosive spraying. Since the flame velocity of is obtained, the energy when the molten flame powder frame collides with the substrate at a high speed is high, and the hardness of the flame is high due to the action, and it is possible to obtain a dense thermal spray coating with few open pores. .. Further, in SPS, the particle size (D ₅₀ ) of a single particle is as small as around 1 μm, so that the residual stress in the splat can be reduced, and micro cracks on the surface of the coating and open pores inside the coating (vertical) The amount of cracks can be reduced as much as possible.

  By using these methods, a dense film with few open pores can be obtained, and particle contamination and invasion of halogen-based corrosive gas can be suppressed. Furthermore, since it is possible to prevent the acid generated by the reaction between the water and the reaction product and the penetration of water during the precision cleaning, and the damage to the member can be suppressed, the life of the member can be further extended.

  The yttrium-based fluoride sprayed coating of the present invention can be formed on the surface of a base material such as a metal or ceramics used in a semiconductor manufacturing apparatus, thereby achieving excellent corrosion resistance and good particle generation prevention. Further, by combining a lower layer of a rare earth oxide sprayed coating made of an oxide of a rare earth and the yttrium fluoride sprayed coating of the present invention to form a corrosion resistant coating having a multi-layer structure, a higher acid permeation suppression effect can be obtained. Therefore, it is possible to more effectively prevent damage to the coating and obtain more reliable corrosion resistance.

  The rare earth element of the rare earth oxide sprayed coating forming the lower layer is selected from Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. The rare earth metal element is preferably used, and more preferably a rare earth metal element selected from Y, Sc, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. These rare earth elements may be used alone or in combination of two or more.

  This lower layer can be formed by spraying the oxide of the rare earth element on the surface of the base material, and the yttrium-based fluoride sprayed coating of the present invention may be laminated thereon to form a composite corrosion resistant coating. For the same reason as above, the lower layer preferably has a porosity of 5% or less of the coating surface area, more preferably 3% or less. Although such a low porosity is not particularly limited, it can be obtained by, for example, the following method.

That is, a single particle powder having a particle diameter of 0.5 to 30 μm (D ₅₀ ), preferably 1 to 20 μm is used as the raw material powder of the rare earth oxide, and the single particle is sufficiently prepared by plasma spraying, SPS spraying, explosive spraying, or the like. By performing melting and thermal spraying, the dense sprayed film of rare earth oxide having few open pores and a porosity of 5% or less can be formed. In this method, since the above-mentioned single particle powder used as the thermal spray material is one in which the content is filled with fine particles having a particle size smaller than that of the general granulated thermal spray powder, the splat diameter is small and crack generation can be suppressed. Due to this effect, a sprayed film having a surface roughness of 5% or less with extremely few open pores and a small surface roughness can be obtained. The “single particle powder” refers to powder having a solid content in the form of spherical powder, horny powder, crushed powder, or the like.

  Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. After that, yttrium oxide powder (horny single particles) having an average particle diameter of 8 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases, with an output of 40 kW and a spraying distance. Thermal spraying was performed at 100 mm and 30 μm/Pass to form a yttrium oxide sprayed coating having a film thickness of 100 μm as a lower layer. When confirmed by an image analysis method, the lower layer had a porosity of 3.2%. The specific method for measuring the porosity is the same as the method for measuring the porosity of the surface layer described later.

On the other hand, 95 mass% of yttrium fluoride powder A having an average particle diameter of 1 μm (D ₅₀ ) and 5 mass% of yttrium oxide powder B having an average particle diameter of 0.2 μm are mixed and granulated by a spray drying method, A thermal spray powder (thermal spray material) was manufactured by firing at 800° C. in a nitrogen gas atmosphere. The particle diameter (D ₅₀ ), bulk density, and angle of repose of this sprayed powder were measured. The results are shown in Table 1. Further, when XRD analysis was conducted on this thermal spray powder, as shown in Table 1, it was composed of YF ₃ and Y ₅ O ₄ F ₇ , and the Y ₅ O ₄ F ₇ ratio was 9.1 mass %. This sprayed powder (sprayed material) is plasma sprayed on the lower layer made of the above-mentioned yttrium oxide sprayed coating under the same conditions as when forming the lower layer to form a surface layer of the yttrium-based fluoride sprayed coating having a thickness of 100 μm. Then, a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

An XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YF ₃ and Y ₅ O ₄ F ₇ , as shown in Table 1. The surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the amount of surface cracks, the porosity, and the hardness HV were measured for the surface sprayed coating. The results are shown in Table 1. The crack amount, porosity, and hardness HV were measured by the following methods.

[Measurement of surface crack amount]
A surface photograph (magnification: 3000) was taken with an electron microscope for each of the obtained test pieces. After shooting 5 fields of view (1 field of view shooting area: 0.0016 mm ² ), after image processing with the image processing software “Photoshop” (Adobe Systems Co., Ltd.), image analysis software “Scion Image” (Scion Corporation) Was used to quantify the amount of cracks. Table 1 shows the results of evaluation of the average crack amount at five locations as a percentage of the total image area.
[Measurement of porosity]
The obtained test piece was filled with resin, the cross section was mirror-finished (Ra=0.1 μm), and then a cross-section photograph (magnification: 200 times) was taken with an electron microscope. After shooting 10 fields of view (shooting area of one field of view: 0.017 mm ² ), image processing was performed with the image processing software “Photoshop” (Adobe Systems Co., Ltd.), and then image analysis software “Scion Image” (Scion Corporation) Was used to quantify the porosity, and the average porosity of 10 visual fields was evaluated as a percentage of the total image area. The results are shown in Table 1.
[Measurement of hardness HV]
The surface and cross section of the obtained test piece were mirror-finished (Ra=0.1 μm), and the hardness of the coating surface was measured with a micro Vickers hardness meter. Three points were measured and the average value was used as the surface hardness of the film. The results are shown in Table 1.

[Example 2]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, an yttrium oxide powder (granulated powder) having an average particle size of 20 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases to obtain an output of 40 kW and a spraying distance of 100 mm. Sprayed at 30 μm/Pass to form a 100 μm thick yttrium oxide sprayed coating as the lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 2.8%.

On the other hand, 90 mass% of yttrium fluoride powder A having an average particle diameter of 1.7 μm (D ₅₀ ) and 10 mass% of yttrium oxide powder B having an average particle diameter of 0.3 μm are mixed and granulated by a spray drying method. Then, it was fired at 800° C. in a nitrogen gas atmosphere to produce a sprayed powder (sprayed material). The particle size of the spray powder (D _50), the bulk density was measured angle of repose. The results are shown in Table 1. Further, when XRD analysis was performed on this thermal spray powder, it was composed of YF ₃ and Y ₅ O ₄ F ₇ , as shown in Table 1, and the Y ₅ O ₄ F ₇ ratio was 17.3 mass %. This sprayed powder (sprayed material) is plasma sprayed on the lower layer made of the above yttrium oxide sprayed coating under the same conditions as when forming the lower layer to form a surface layer of the yttrium-based fluoride sprayed coating having a thickness of 100 μm. Then, a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

An XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YF ₃ and Y ₅ O ₄ F ₇ , as shown in Table 1. Further, the surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the surface crack amount, the porosity, and the hardness HV of the thermal spray coating of the same surface layer were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
The surface of a 20 mm square (5 mm thick) alumina ceramic substrate was degreased with acetone, and one surface of the substrate was roughened using a corundum abrasive. After that, yttrium oxide powder having an average particle diameter of 30 μm (D ₅₀ ) was sprayed at a spraying distance of 100 mm at 15 μm/Pass using an explosive spraying device, and oxygen and ethylene gas were used to deposit yttrium oxide having a film thickness of 100 μm. A thermal spray coating was formed as a lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 1.8%.

On the other hand, 85 mass% of yttrium fluoride powder A having an average particle diameter of 1.4 μm (D ₅₀ ) and 15 mass% of yttrium oxide powder B having an average particle diameter of 0.5 μm were mixed by a ball mill, and the mixture was placed in a nitrogen gas atmosphere. And fired at 800° C. to produce a sprayed powder (sprayed material). The particle diameter (D ₅₀ ) of this sprayed powder was measured. The results are shown in Table 1. Further, when XRD analysis was performed on this thermal spray powder, as shown in Table 1, it was composed of YF ₃ and Y ₅ O ₄ F ₇ , and the Y ₅ O ₄ F ₇ ratio was 26.4 mass %. Using this sprayed powder (sprayed material) and pure water, a slurry having a slurry concentration of 30 mass% was prepared. On the lower layer composed of the yttrium oxide sprayed coating, an atmospheric pressure plasma spraying device was used, and argon gas, nitrogen gas, and hydrogen gas were used as plasma gases, and the output was 100 kW and the spraying distance was 70 mm, and the SPS was 30 μm/Pass. Thermal spraying was performed to form a surface layer of the yttrium-based fluoride sprayed coating having a film thickness of 100 μm, and a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YF ₃ , YOF and Y ₂ O ₃ , as shown in Table 1. Further, the surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the surface crack amount, the porosity, and the hardness HV of the thermal spray coating of the same surface layer were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, yttrium oxide powder (spherical single particles) having an average particle diameter of 18 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases, with an output of 40 kW and a spraying distance of 100 mm. Was sprayed at 30 μm/Pass to form a 100 μm thick yttrium oxide sprayed coating as a lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 2.8%.

On the other hand, yttrium fluoride granulated powder A having an average particle diameter of 45 μm (D ₅₀ ) and yttrium oxide granulated powder B having an average particle diameter of 40 μm are mixed at a mixing ratio of 90:10 (mass ratio) to form a mixed powder. A spray powder (spray material) was produced. The particle size of the spray powder (D _50), the bulk density was measured angle of repose. The results are shown in Table 1. Further, when XRD analysis was performed on this thermal spray powder, it was in a state where YF ₃ and Y ₂ O ₃ were mixed as they were, as shown in Table 1. This sprayed powder (sprayed material) is plasma sprayed on the lower layer made of the above-mentioned yttrium oxide sprayed coating under the same conditions as when forming the lower layer to form a surface layer of the yttrium-based fluoride sprayed coating having a thickness of 100 μm. Then, a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YF ₃ , Y ₅ O ₄ F _7, and Y ₂ O ₃ as shown in Table 1. .. Further, the surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the surface crack amount, the porosity, and the hardness HV of the thermal spray coating of the same surface layer were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, an yttrium oxide powder (granulated powder) having an average particle size of 20 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases to obtain an output of 40 kW and a spraying distance of 100 mm. Sprayed at 30 μm/Pass to form a 100 μm thick yttrium oxide sprayed coating as the lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 2.8%.

  On the lower layer made of this yttrium oxide sprayed coating, yttrium fluoride granulated powder A having an average particle diameter of 40 μm was used alone as a thermal spraying material, and plasma spraying was performed under the same conditions as when forming the lower layer. A surface layer of the yttrium-based fluoride thermal spray coating was formed to prepare a test piece having a two-layer structure corrosion-resistant coating with a total thickness of 200 μm. The XRD analysis is performed in the same manner as in Example 1, and the bulk density and angle of repose of the sprayed powder, and the surface roughness Ra, Y concentration, F concentration, O concentration, C concentration, surface crack amount, porosity of the surface layer, The hardness HV was measured. The results are shown in Table 1.

[Comparative example 2]
The surface of a 20 mm square (5 mm thick) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, yttrium fluoride granulated powder A having an average particle diameter of 30 μm (D ₅₀ ) was used at atmospheric pressure plasma spraying apparatus, argon gas and hydrogen gas were used as plasma gas, at an output of 40 kW and a spraying distance of 100 mm. Thermal spraying was performed at 30 μm/Pass to form a yttrium fluoride sprayed coating having a film thickness of 200 μm. Thus, a test piece having a corrosion resistant coating composed of a single layer of the yttrium fluoride sprayed coating was prepared. The XRD analysis is performed in the same manner as in Example 1, and the bulk density and repose angle of the sprayed powder, the surface roughness Ra, Y concentration, F concentration, O concentration, C concentration, surface crack amount, porosity of the sprayed coating, The hardness HV was measured. The results are shown in Table 1.

[Comparative Example 3]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, an yttrium oxide powder (granulated powder) having an average particle size of 20 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases to obtain an output of 40 kW and a spraying distance of 100 mm. Sprayed at 30 μm/Pass to form a 100 μm thick yttrium oxide sprayed coating as the lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 2.8%.

On the other hand, 65 mass% of yttrium fluoride powder A having an average particle diameter of 1 μm (D ₅₀ ) and 35 mass% of yttrium oxide powder B having an average particle diameter of 0.2 μm are mixed and granulated by a spray drying method, A thermal spray powder (thermal spray material) was manufactured by firing at 800° C. in a nitrogen gas atmosphere. The particle diameter (D ₅₀ ), bulk density, and angle of repose of this sprayed powder were measured. The results are shown in Table 1. Further, when XRD analysis was performed on this thermal spray powder, as shown in Table 1, it was composed of YF ₃ and Y ₅ O ₄ F ₇ , and the Y ₅ O ₄ F ₇ ratio was 49.8 mass %. This sprayed powder (sprayed material) is plasma sprayed on the lower layer made of the above-mentioned yttrium oxide sprayed coating under the same conditions as when forming the lower layer to form a surface layer of the yttrium-based fluoride sprayed coating having a thickness of 100 μm. Then, a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YOF, Y ₅ O ₄ F ₇ and Y ₇ O ₆ F ₉ as shown in Table 1. .. Further, the surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the surface crack amount, the porosity, and the hardness HV of the thermal spray coating of the same surface layer were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
The surface of a 20 mm square (thickness 5 mm) A6061 aluminum alloy base material was degreased with acetone, and one surface of the base material was roughened using a corundum abrasive. Then, an yttrium oxide powder (granulated powder) having an average particle size of 20 μm (D ₅₀ ) was used by using an atmospheric pressure plasma spraying apparatus, and argon gas and hydrogen gas were used as plasma gases to obtain an output of 40 kW and a spraying distance of 100 mm. Sprayed at 30 μm/Pass to form a 100 μm thick yttrium oxide sprayed coating as the lower layer. When confirmed by an image analysis method as in Example 1, the lower layer had a porosity of 2.8%.

On the other hand, 50 mass% of yttrium fluoride powder A having an average particle diameter of 1 μm (D ₅₀ ) and 50 mass% of yttrium oxide powder B having an average particle diameter of 0.2 μm are mixed and granulated by a spray drying method, A thermal spray powder (thermal spray material) was manufactured by firing at 800° C. in a nitrogen gas atmosphere. The particle diameter (D ₅₀ ), bulk density, and angle of repose of this sprayed powder were measured. The results are shown in Table 1. Further, XRD analysis of this thermal spray powder revealed that it was composed of YF ₃ , Y ₅ O ₄ F _7, and Y ₂ O ₃ as shown in Table 1, and the Y ₅ O ₄ F ₇ ratio was 59.1% by mass. It was This sprayed powder (sprayed material) is plasma sprayed on the lower layer made of the above yttrium oxide sprayed coating under the same conditions as when forming the lower layer to form a surface layer of the yttrium-based fluoride sprayed coating having a thickness of 100 μm. Then, a test piece having a two-layer structure corrosion-resistant coating having a total thickness of 200 μm was produced.

XRD analysis of the surface layer of the yttrium-based fluoride thermal spray coating revealed that it had a yttrium-based fluoride crystal structure composed of YOF and Y ₅ O ₄ F ₇ , as shown in Table 1. Further, the surface roughness Ra, the Y concentration, the F concentration, the O concentration, the C concentration, the surface crack amount, the porosity, and the hardness HV of the thermal spray coating of the same surface layer were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained test pieces of Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated for particle generation and plasma corrosion resistance by the following tests. The results are shown in Table 1.
[Particle generation evaluation test]
Each test piece was subjected to ultrasonic cleaning (output 200 W, cleaning time 30 minutes), dried, and then immersed in 20 cc of ultrapure water for further 15 minutes of ultrasonic cleaning. After ultrasonic cleaning, take out the test piece, add ₂ cc of 5.3N nitric acid solution to dissolve the Y ₂ O ₃ fine particles contained in the ultrapure water, and measure the quantitative value of Y ₂ O ₃ by ICP emission spectrometry. did. The results are shown in Table 1.
[Corrosion resistance evaluation test]
The surface of each test piece is mirror-finished (Ra=0.1 μm), a masked tape masked portion and an exposed portion are formed, and then the test piece is set in a reactive ion plasma tester, with a frequency of 13.56 MHz and plasma output. The plasma corrosion resistance test was conducted under the conditions of 1000 W, gas species CF ₄ +O ₂ (20 vol %), flow rate 50 sccm, gas pressure 50 mtorr, and 20 hours. Using a laser microscope, the height of the step formed between the exposed portion and the masked portion due to corrosion was measured with a laser microscope, and the average value of the four measurement points was calculated to evaluate the corrosion resistance. The results are shown in Table 1.

  As shown in Table 1, the yttrium fluoride thermal spray coatings of Examples 1 to 4 according to the present invention have less cracks and open pores and higher hardness than the thermal spray coatings of Comparative Examples 1 to 4. It was confirmed to be a dense film. In this case, FIGS. 1 and 2 show analysis image photographs of the surface of the sprayed coating of Comparative Example 1, and FIGS. 3 and 4 show analysis image photographs of the surface of the sprayed coating of Example 2. By comparing FIGS. 1 and 2 with FIGS. 3 and 4, it is clearly confirmed that the thermal spray coating of the present invention has far fewer cracks than the conventional coating.

Further, the corrosion-resistant coatings of Examples 1 to 4 containing the yttrium-based fluoride sprayed coating of the present invention as the surface layer had a Y ₂ O ₃ elution amount in the above particle generation evaluation test as compared with the coatings of Comparative Examples 1 to 4. It was confirmed that the number of particles was far less and that the generation of fine particles could be effectively prevented. Further, it was confirmed that the corrosion-resistant coatings of Examples 1 to 4 had a much smaller step height caused by corrosion in the above-mentioned corrosion resistance test than the coatings of Comparative Examples 1 to 4, and were excellent in corrosion resistance to plasma etching. It was

Claims (9)

A yttrium-based fluoride thermal spray coating having a thickness of 10 to 500 μm formed on the surface of a base material, having a yttrium-based fluoride crystal structure containing YF ₃ and Y ₅ O ₄ F ₇ and/or YOF, and oxygen. concentration 2-4 wt%, hardness 350~470HV der is, 5% of the cracks weight film surface area or less, and yttrium-based fluoride thermal spray coating porosity and wherein 5% der Rukoto coating surface area. The yttrium fluoride thermal spray coating according to claim 1, which has a yttrium fluoride crystal structure composed of YF ₃ and Y ₅ O ₄ F ₇ and/or YOF. The yttrium fluoride thermal spray coating according to claim 1 or 2 , wherein the carbon content is 0.01% by mass or less. Claim 1 is a thermal spray material to form a yttrium-based fluoride spray coating according to any one of 3, granulated powder balance YF ₃ 9 to 27 mass% in Y ₅ O ₄ F ₇ An yttrium-based fluoride thermal spray material characterized by comprising: It is a thermal spray material for forming the yttrium fluoride thermal spray coating according to any one of claims 1 to 5 , and is a granulated powder of yttrium fluoride of 95 to 85 mass% and a granulated powder of yttrium oxide of 5 to 5. A yttrium-based fluoride thermal spray material, which is a mixed powder containing 15% by mass. A method for forming the yttrium-based fluoride thermal spray coating according to any one of claims 1 to 5 , which is formed by thermal spraying using the yttrium-based fluoride thermal spray material according to claim 4 or 5. And a method for forming a yttrium-based fluoride sprayed coating. The method for forming a yttrium-based fluoride sprayed coating according to claim 6 , wherein the spraying is plasma spraying. Multiple having a lower layer a thickness of the rare earth oxide sprayed coating having a porosity of 5% or less at 10 to 500 [mu] m, and an outermost layer made of yttrium-based fluoride sprayed coating according to any one of claims 1 to 3 A corrosion-resistant coating having a layered structure. 9. The corrosion resistance according to claim 8 , wherein the rare earth metal element of the lower layer rare earth oxide sprayed coating is one or more selected from Y, Sc, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Film.